The last decade has seen a dramatic increase in the use of polymer membranes as an effective, economical and flexible tool for many gas separations. The processability, gas solubility, and selectivity of several classes of polymers (such as polyimides, polysulfones, polyesters and the like) have led to their use in a number of successful gas separation applications. A drawback to the use of polymer membranes for gas separation can be their low permeability. In most instances, the success of a given membrane rests on achieving adequate fluxes.
The commercial use of polymer membranes for air separation, the recovery of hydrogen from mixtures of nitrogen, carbon monoxide and methane, and the removal of carbon dioxide from natural gas has been reported. In each of these applications, high fluxes and excellent selectivities have relied upon glassy polymer membranes which rely on gas size differences for separation of species. Yet, this technology has focused on optimizing separation materials for near ambient conditions. The development of polymeric materials that achieve good combinations of high selectivity, high permeability, mechanical stability and processability at temperatures above about 25° C. and pressures above about 10 bar has been needed.
Separation of carbon dioxide (CO2) from mixed gas streams is of major industrial interest. Continued improvements in such separations are sought. Commercially viable membrane-based approaches to industrial CO2 separations require reduction in costly drops in operating temperatures and pressures while maintaining high fluxes. The need for higher flux CO2 separation approaches remains.
Other research efforts have been directed to the development of polymer membranes that operate at elevated temperatures and pressures.
Through the efforts of the present inventors, a polymer membrane design has now been achieved which can operate under high fluxes. Such a polymer membrane design involves a meniscus-shaped polymer membrane within one or more small pore or opening. That polymer membrane design allows for a number of varying applications described herein.
It is an object of this invention to provide a polymer membrane capable of operation under high fluxes.
It is another object of this invention to provide a meniscus-shaped polymer membrane within one or more small pore or opening, the meniscus-shaped polymer membrane contained substantially completely within such small pores or openings.
Still another object of the present invention is a process for rapidly screening polymers for membranes in non-ambient gas separations by use of such a meniscus-shaped polymer membrane.
Still another object of the present invention is the use of a meniscus-shaped polymer membrane as a selective pre-screen, e.g., for a sensor system including a sensor element where the meniscus-shaped polymer membrane can serve to screen out molecules that would contaminate the sensor element.
Still another object of the present invention is the use of a meniscus-shaped polymer as a pressure/temperature sensor element.
Still another object of the present invention is the use of a meniscus-shaped polymer as a pre-concentrator for a gas stream prior to entry into, e.g., a mass spectrometer.
Still another object of the present invention is the use of a meniscus-shaped polymer as a temperature controlled valve in a gas separation system.